Field Notes
Field Notes

One National Park, eight lakes, two million water quality clues

Monday, November 18, 2019
Posted by
Greg Seitz

Mohan, Engstrom, and Edlund set off with canoe and gear to study a remote Isle Royale lake. (Photo by Mark Edlund)

This August, Dr. Mark Edlund, working with colleagues from the station, the National Park Service, University of Maine, and St. Olaf College, returned to Isle Royale National Park for 10 days of paddling, portaging, and collecting information from remote lakes in the National Park in Lake Superior. The team included Research Station director emeritus Dr. Dan Engstrom, and Joe Mohan, a PhD student from University of Maine, whose advisor, Dr. Jasmine Saros, is the other lead principal investigator on the project.

The trip culminated two years of study to determine if these wild waters are changing, and why. With instruments submerged in the lakes taking readings every 30 minutes, more devices deployed to collect sediment sinking to the bottom, and other extensive efforts, the scientists are trying to answer pressing questions.

In recent years, blooms of cyanobacteria, algae that produce toxins, have been spotted in some Isle Royale lakes. But almost the whole park is federally-designated wilderness and hasn’t changed much in decades. There haven’t been any new farm fields plowed, or residential neighborhoods developed, or wastewater treatment plants discharging upstream — the usual reasons for such noxious conditions.

Field work video by David Burge:

Nonetheless, the algae have been blooming. So the scientists set out to study the lakes and their watersheds, reconstruct historic water quality, and investigate connections between land, climate, atmosphere, and water. A few key questions have come up. 

Has it always been this way? Cyanobacteria are natural organisms, only becoming a problem in certain conditions — warm, nutrient-rich water is ideal. Human memories are imperfect, so scientists need data to determine if this is a new problem or not.

If it’s a new or increasing phenomenon, why is that? It could be climate change — not just global warming but also changes to wind and precipitation patterns. Or additional nutrients could be carried from afar on the wind. 

Maybe forest fire frequency has changed, decreasing runoff. Or some other subtle changes may have occurred in the lakes and the areas affecting them. There were many maybes but not much reliable information.

Edlund and Mohan work together on the shores of an Isle Royale interior lake, extracting material for DNA analysis. (Photo by Dan Engstrom)

That's how the field crew found themselves bushwacking into rarely-visited lakes.Seeking to solve these mysteries has meant some long hikes and recordingdata that can contain critical clues.

When the team pulled their sensors and sediment traps from the lakes this summer, they wrapped up one phase of the project. Pieces of an explanation hopefully reside In all the sediment samples and computer databases. Now comes the analysis. 

Stay tuned for part three of this trilogy.

The National Park Service recently published an article in Isle Royale’s Greenstone newsletter (PDF).

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